多普勒声雷达测风与直接测量仪器的观测比较

文中对多普勒声雷达测风和325 m铁塔上风速、风向仪及超声风速仪的测量值进行了观测比较。结果表明,当信噪比大于1时,两种方法测量的平均风速、风向的相关较好,风速、风向廓线较为接近;声雷达测量的垂直风速平均值和均方根差比超声风速仪的测量值略偏大。这与国外进行的观测比较结果一致。 需要指出,声雷达和直接测量仪器的观测比较中存在一定差异,特别是对比每一次的观测值就可以看出,在某些情况下还存在明显差异。进一步分析声雷达测风产生偏差的原因,对误差做出合理的订正是十分必要的。     

Wavy Vertical Motions in the ABL Observed by Sodar

Some characteristics of wavelike motions in the atmospheric boundary layer observed by sodar are considered. In an experiment carried out in February 1993 in Milan, Italy, Doppler sodar measurements were accompanied by in situ measurements of temperature and wind velocity vertical profiles using a tethered balloon up to 600 m. The oscillations of elevated wavy layers containing intense thermal turbulence, usually associated with temperature-inversion zones, were studied by using correlation and spectral analysis methods. The statistics of the occurrence of wavelike and temperature-inversion events are presented. The height distributions of Brunt–Vaisala frequency and wind shear and their correlation within elevated inversion layers were determined, with a strong correlation observed between the drift rate of the wavy layers and the vertical velocity measured by Doppler sodar inside these layers. Spectral analysis showed similarities regarding their frequency characteristics. The phase speed and propagation direction of waves were estimated from the time delay of the signals at three antennae to provide estimates of wavelength. Moreover, wavelengths were estimated from the intrinsic frequency obtained from sodar measurements of the Doppler vertical velocity and oscillations of wavy turbulent layers. The two wavelength estimates are in good agreement.     

Corrections for Wind-Speed Errors from Sodar and Lidar in Complex Terrain

The quality of lidar and sodar wind estimates is generally judged through comparisons with mast-mounted instruments, and the resulting regressions. Evaluation of the relative merits of lidars versus sodars is complicated by the fact that lidars are generally placed close to a mast whereas sodars are generally placed some distance from a mast so that acoustic reflections off the mast are reduced. This leads to the two technologies, lidar and sodar, not being compared in similar situations. Differences arising from the two geometries can be expected to be larger in complex terrain, where the wind regime can vary significantly spatially. The current work explores these differences in moderately complex terrain. Lidar–mast comparisons are performed with the lidar close to an 80 m mast, and sodar–mast comparisons performed with the sodar 300 m from the mast. Systematic variations in estimated wind speed are found to occur with height, consistent with predictions from a simple flow model. When the lidar was moved to the sodar location, further from the mast, there were significant changes in the estimated wind speeds and a reduction in correlation with the mast-based wind speeds, as expected. However, the correlation between collocated lidar and sodar winds was high. This finding emphasizes that any comparison of two remote sensing instruments needs to be through similar experiments, and that differences in accuracy often reported for the lidar and sodar technologies are likely to be contaminated due to poor comparison configurations. A method was devised to simulate the sodar being collocated with the mast, by using the lidar–sodar measurements and the lidar–mast measurements. It was found that there was then no statistically detectable difference between lidar–mast regressions and sodar–mast regressions for the particular lidar and sodar tested. Both remote sensing instruments were also found to be good estimators of Weibull parameters, as compared with those derived from mast data. The conclusion is that the sodar measured the winds above the sodar with a similar accuracy to the lidar measuring winds above the lidar.     

Mean wind speed profiles in the air basin of Moscow

Results of measurements of mean wind speed profiles and direction during two years in the center of the city of Moscow are presented. These measurements were performed with a Doppler acoustic profiler (sodar), which was used for continuous monitoring of the wind speed within the height range from 40 to 250–500 m. The averaged seasonal mean profiles are presented along with other observational data, including diurnal cycle parameters, wind speed and direction frequencies at chosen levels, and frequencies and duration of strong winds and calm weather.     

Use of a High-Resolution Sodar to Study Surface-layer Turbulence at Night

Measurements in the atmospheric surface layer are generally made with point sensors located in the first few tens of metres. In most cases, however, these measurements are not representative of the whole surface layer. Standard Doppler sodars allow a continuous display of the turbulent thermal structure and wind profiles in the boundary layer up to 1000 m, with a few points, if any, in the surface layer. To overcome these limitations a new sodar configuration is proposed that allows for a higher resolution in the surface layer. Because of its capabilities (echo recording starting at 2 m, echo intensity vertical resolution of approximately 2 m, temporal resolution of 1 s) this sodar is called the surface-layer mini-sodar (SLM-sodar). Features and capabilities of the SLM-sodar are described and compared with the sodar. The comparison of the thermal vertical structure given by the SLM-sodar and the sodar provides evidence that, in most cases, the surface layer presents a level of complexity comparable to that of the entire boundary layer. Considering its high vertical resolution, the SLM-sodar is a promising system for the study of the nocturnal surface layer. The nocturnal SLM-sodar measurements have shown that, depending on wind speed, the structure of the surface layer may change substantially within a short time period. At night, when the wind speed is greater than 3 m s⁻¹, mechanical mixing destroys the wavy structure present in the nocturnal layer. Sonic anemometer measurements have shown that, in such cases, also the sensible heat flux varies with height, reaching a peak in correspondence with the wind speed peak. Under these conditions the assumption of horizontal homogeneity of the surface layer and the choice of the averaging time need to be carefully treated.     

Characteristics of wind speed and wind direction in the atmospheric boundary layer on the southern coast of Bulgaria

The characteristics of wind speed and wind direction in the boundary atmospheric layer measured at the meteorological station in Akhtopol (Bulgaria) are presented. The measurements were carried out with the Scintec sodar and MK-15 automatic meteorological station. The sodar measurement data on wind parameters at different heights in different months are presented as well as the frequency of inshore and offshore wind directions, that enables to trace the intensity of the breeze circulation. The frequency of calms and wind speeds at the heights of 50, 100, and 200 m according to gradations for different months and the probability of wind of various speeds depending on the direction are also given. The breeze front characteristics in June–September of 2009 are computed from the speed and direction of surface wind measured with the acoustic anemometer of MK-15 complex.     

Detection of Inversions and Mixing Height by REMTECH PA2 Sodar in Comparison with Collocated Radiosonde Measurements

Summary A REMTECH PA2 Doppler Sodar is operated regularly at the Czech Hydrometeorological Institute (CHMI) observatory in Prague, collocated with a routine rawinsonde sounding system. The Air Pollution Control Division of CHMI utilises the sodar data in air pollution studies and as an information support for the smog warning system operated in Prague. Besides of the basic software for echo strength and wind profile evaluation, optional routines for deriving parameters such as inversion and mixing height, stability class etc. were delivered by the sodar manufacturer. Based on a sufficiently large data set (more than one year) of synchronous sodar and rawinsonde measurements, an analysis and comparison of inversion and mixing heights provided by both sounding systems have been accomplished in order to evaluate the correctness and accuracy of sodar estimates of these parameters. In contrast to the wind speed and wind direction data, for which a satisfactory agreement with other kind of measurements has been reported by many studies, the results for inversion and mixing height detection were totally disappointing. A direct applicability of inversion height and mixing height data provided by the REMTECH’s automatic routines in air pollution studies or smog warning systems is quite problematical with the present “state of the art”. Received November 3, 1998 Revised April 20, 1999     

山东高分辨率风能资源分布特征的数值模拟研究

基于WRF3.8.1数值模式,利用FNL 1°×1°再分析资料,对山东边界层10 m、70 m、100 m等高度2017年风场进行了逐日动力降尺度模拟,使用山东122个气象站逐日平均风速,对模拟结果进行了客观评估。结果表明：WRF模式可以较好地模拟出山东逐日平均风速变化特征,但模拟值普遍大于实测值,山东不同区域平均风速模拟效果差异较大,四季误差分析结果与全年略不同;山东沿海、半岛北部丘陵、崂山、日照中部五莲山、鲁中山区各山脉等区域以及微山湖、东平湖等大型湖泊区域年和四季10 m、70 m、100 m高度平均风速、平均风功率密度较大,大汶河、大清河、泗水河、沂河及其支流、淄河、潍河等流域中上游的山区间低矮平原地带较小,但各地风能资源的差异随高度增加而明显减小。平均风速、平均风功率密度时空分布结果可为山东内陆地区分散式低风速风电场的选址、风能资源开发利用提供参考。     

Turbulence structure in temperature inversions and in convection fields as observed by doppler sodar

The structure of turbulence in an inversion layer and in an homogeneous convective field of the planetary boundary layer is described. In the first part of the paper, we validate the sodar estimates of turbulent dissipation, by using measurements with an hot-wire anemometric system in situ. Limitations of an ε measurement technique using structure function calculations are given, taking account of atmospheric properties and acoustic Doppler instrumental effects. By comparison between isopleths of backscattering intensity and of turbulent dissipation rates, we observe that in the early morning, turbulence is advected by mechanical turbulence generated by wind shear. The same mechanism seems to be operating in the case of an inversion layer capping thermal instability, when the convective activity is not too greatly developed. A turbulent kinetic energy budget is examined using aircraft, sodar, and tower measurements. This indicates a constant turbulent dissipation profile through a deep convective layer.     

由声雷达回波反演湍流场结构系数

定量测量声雷达回波强度可以导出大气温度结构系数（Ct 2）和速度结构系数（Cv2）。文章简要回顾和评述了过去的工作，并讨论了逾量衰减、风和湍流等因素对该测量的影响。研究表明:逾量衰减主要是由速度场的不均匀性所造成。其次，风场也有不可忽视的衰减作用，在风速达10 m/s时，引起的衰减达50%以上。最后给出了改进后的声雷达方程和反演Ct2和Cv2的方法。初步的试验结果对理论的应用是支持的。     

DOPPLER SODAR AND ATMOSPHERIC BOUNDARY LAYER DETECTION

A Doppler sodar system controlled by microcomputer is described in this paper. The sodar was usedto detect the vertical distribution of wind and temperature stratification in the atmospheric boundary layer.The detecting results show that at night the vertical distribution of wind is very complicated, which can appearas a structure of two or three layers. In nocturnal atmospheric boundary layer sometimes there exists verythin layer in multi-layer inversion and it can be retained for a long time.     

Composing the diurnal cycle of mixing height from simultaneous sodar and wind profiler measurements

Mixing heights have been determined independently from sodar and boundary-layer wind profiler measurements carried out at the Meteorological Observatory Lindenberg of the German Weather Service between 1 June 1994 and 6 July 1994. Good agreement between both systems was found for mixing height values between about 250 m and 700 m, i.e., in an evolving convective boundary layer. Considering the typical sounding ranges of the sodar (50 m up to 800 m) and of the wind profiler (200 m up to higher than 3000 m), simultaneous operation of the two systems is demonstrated to be a promising tool for continously monitoring the mixing height throughout its complete diurnal cycle.     

Observations of Atmospheric Solitary Waves in the Urban Boundary Layer

The simultaneous operation of a three-axis Doppler sodar system in the centralurban area of Rome and two similar systems in the suburban area, forming atriangle about 20 km on each side, provided evidence of solitary-type wavesin the urban boundary layer. Three events, each lasting from a few minutes toabout 30 min, and ranging in depth from the minimum range of the sodar (39 m) to over 500 m, are reported here. Two events were recognizable onall three sodar records while the third event could be observed at the urbanlocation only. Time-height acoustic echo intensity records showed no-echoregions within the wave indicating transport of trapped recirculating air.This is typical of large amplitude solitary waves. The time series plots ofsodar-derived vertical wind velocity revealed a maximum peak-to-peakvariation of about 5 m s^-1 during periods of wave-associated disturbance.The vertical velocity is found to increase with height up to the top of the closedcirculation within the wave and decreases further above. The normalisedamplitude-wavelength relationship for the two events indicates that theobserved waves are close to a strongly nonlinear regime.     

Foehn signals detected by sodar wind and turbulence measurements in the Rhine Valley, Austria, during the MAP field phase

Summary Within the Mesoscale Alpine Programme MAP conducted in autumn 1999, the vertical structure and the temporal evolution of the planetary boundary layer (PBL) in the Rhine Valley 2km south of Lake Constance were observed with a Remtech PA2 sodar (sound-detection-and-ranging instrument) rendering half-hour averages of the three-dimensional wind profile within the lowest kilometre above ground. During Foehn events, tethered balloon soundings and wind profiler measurements were conducted in addition to the rawinsonde network which was built up for the MAP field campaign.The remote sensing instrument renders a surprisingly high number of valid data during south Foehn. Due to the frequent formation of a cold air pool with stable conditions below the Foehn flow with near-neutral static stability, even more sodar data is valid during Foehn periods than during no Foehn periods. A significant reduction of the sodar data quality is only observed during Foehn events with grounding of the Foehn at the sodar site due to high background noise. At higher levels, a Foehn signal can be detected from the sodar wind and turbulence intensitiy information. With Foehn, higher wind speeds and larger turbulence intensities occur than without Foehn. Comparisons to rawinsonde and tethersonde soundings and wind profiler measurements at sites nearby reveal the spatial inhomogeneity of the Foehn flow within this part of the valley as well as instrumental short-comings. Different methods to determine the mixing height using the vertical sounding devices lead to some uncertainty of mixing height estimates which however can reasonably be explained.     

声雷达定量测量C_T~2中的几个问题

本文讨论了逾量衰减和风对声线的弯曲作用对声雷达接收功率的影响.分析和计算表明在很多情况下分子吸收、逾量衰减和风的影响对测量C_T~2是不能忽略的,不考虑这些因素有时可使C_T~2低估500％以上.引进有效湍流外尺度后使声散射截面表达式在实际应用中变得合理而简单.由简化的几何模型导出了风衰减因子,经计算和以往的实验事实相符.因此在原声雷达方程中应加入风衰减因子.声雷达方程加上逾量衰减算式、风衰减算式和分子衰减算式,组成了适合定量测量C_T~2的声雷达方程组.利用温度脉动仪测定低高度上的C_T~2值可使估算工作简化,此方法在多普勒声雷达上应用效果会较好,本文并给出了初步实验结果.     

Atmospheric thermic structure studied by acoustic echo sounder, boundary layer model, and direct measurements

In this work, the thermic structure of the atmospheric boundary layer is analyzed by means of direct measurements with radiosonde equipment, remote exploration with a three-monostatic Doppler sodar, and a boundary layer model of order one-and-a-half. Intercomparisons of radiosonde data, sodar data, and model results are made through the study of radiative nocturnal inversion, subsidence inversion, development and height of the mixing layer, and calculus of the temperature structure parameter. The ability of sodar to find the mixing layer height and to detect stable layers is enhanced when these layers are low enough.     

Evidence of Organized Large Eddies by Ground-Based Doppler Lidar, Sonic Anemometer and Sodar

In an experiment investigating the planetary boundary layer (PBL) wind and temperature fields, and PBL inversion height recorded by various instruments, the results reveal the presence of organized large eddies (OLE) or rolls. The measurements by lidars, anemometers, soundings and sodar gave an overview of the characteristics of the rolls and sources of energy production that maintain them. The experimental results obtained on two consecutive days are compared to model outputs. The agreement is excellent, showing that thermal stratification and wind shear are important factors in the structure and dynamics of OLE. A heterodyne Doppler lidar (HDL) is shown to be a useful tool in the study of OLE.     

Wind regime in the lower atmosphere over Moscow from the long-term acoustic sounding data

Presented are the results of the sounding of the lower atmospheric 500-meter layer for the period of 2004–2012 carried out at the Meteorological Observatory of the Moscow State University (MSU) with the MODOS Doppler acoustic radar (sodar) produced by METEK (Germany). Discussed is the methodological basis of the sodar wind data analysis. It is demonstrated that in the air layer up to 200 m the maximum values in the annual course of the wind speed are observed more often in autumn and winter, and the minimum values, in summer; this is associated with the fact that during the cold period of the year Moscow is often located in the zones of intense gradient currents. The diurnal course of the wind speed is characterized by the daytime maximum and night-time minimum in the layer up to 40–60 m from the surface; it is poorly pronounced and characterized by the minimum in the morning in the layer of 80–120 m; and the daytime minimum and night-time maximum are observed above 140–160 m. The layer from 80 to 120 m approximately corresponds to the height of the wind rotation. The amplitude of diurnal variations of the wind speed increases from 0.3 m/s at the height of 7 m and 0.6 m/s at the height of 15 m, to 4.5 m/s at the height of 400 m; however, its secondary minimum (0.5 m/s) associated with the rotation height is registered at the altitude of 80 m. The statistical relationship between the wind speed and surface air temperature is direct during the cold season, inverse during the warm season, and is absent in April and October. The average maximum wind speed over Moscow for ten minutes in the layer up to 500 m from the surface reaches 30–35 m/s in some cases if two conditions concur: the capital is located on the periphery of vast pressure formations (usually of deep cyclones) and the local low-level jet stream is present in the wind profile.     

不同天气条件下脉冲激光风廓线仪测风性能

将2012年5月21日-8月16日广东省湛江市东海岛气象观测站内脉冲激光风廓线仪WINDCUBE V2与气象站内的100 m测风塔进行同步观测试验,在经过观测数据同步性调整、有效性检验和代表性样本筛选基础上,分大小风和有无降雨天气过程,对杯式测风仪、超声风速仪与激光风廓线仪的同步测风数据进行比较,结果显示:脉冲激光风廓线仪与杯式测风仪测量水平风参数的相关性较好,10 min平均风速、风向的线性拟合度均大于0.99,3 s阵风风速的拟合度大于0.96,湍流强度的拟合度大于0.67,风速标准差的拟合度大于0.79;大风情况下,激光风廓线仪对风参数的测量效果更佳。无降雨情况下,激光风廓线仪的测量效果较降雨时略好,10 min降水量小于15 mm的降雨对这款激光风廓线仪的风速、风向、湍流强度、3 s阵风风速的测量没有显著影响,对风速标准差有一定影响。当水平风速增大和有降雨时,激光风廓线仪对垂直速度的测量效果欠佳。该对比分析可为激光风廓线仪观测数据的可靠性提供参考。     

The local wind field at Ny-Å lesund and the Zeppelin mountain at Svalbard

Summary Using a triaxial Doppler sodar the planetary boundary-layer structure and the wind flow dynamics at the Arctic site Ny-?lesund have been studied. The relationship between winds measured at Ny-?lesund and at the nearby atmospheric research station on Zeppelin mountain was investigated for the first time. While Ny-?lesund receives predominantly katabatic flow (from 120°) from the Kongsvegen glacier, the field is rotated within the lowest 500 m and arrives at Zeppelin from southerly directions. Received January 12, 2000/Revised November 21, 2000